Noise reduction -why the rage now ?

Two, many reports of lower noise (in the last 10 years) were in systems with linear power supplies, not switch-mode.

Benchmark Media would not agree with it.  They lowered noise in their DAC by 10dB (S/N= 116dB to 128dB) by replacing linear power supply with SMPS.
Their power amp AHB2 has SMPS and is one of the quietest power amps available (S/N=132dB).  Technical director John Siau claims that such noise performance is not even obtainable with linear supply.  All their products contain SMPS.  Same goes for Rowland.  Rowland uses them in all products including preamps, where efficiency is not important.  They explain benefits of SMPS in application notes on their website.  

Most of linear supplies are in fact primitive switchers that operate at 120Hz.  They switch at maximum voltage and produce current spikes of huge amplitude.  They also produce very narrow voltage spikes, when rectifier diodes at the peak of the full wave sinewave get polarized in reverse direction.  These extremely fast spikes can couple to any circuit.  In contrast, well designed SMPS, switches in zero current, zero voltage and produces very little noise, that is easy to filter out (because of high frequency).   SMPS is also line and load regulated with fast response to line and load changes, while linear supply in power amps is completely unregulated and needs a lot of capacitance to keep amp quiet and voltage steady.  Since these large electrolytic capacitors are inductive they slow down response to fast transitions.

SMPS got bad rap from crude applications on computer power supplies and such cheap things as dimmers.

So why still so many linear power supplies?  For two reasons IMHO.  Because designing high quality SPMS is not easy and because most of people (including you) still believe that SMPS are very noisy (designers simply respond to demand)

I don’t think SMPS are noisy, today. In the past, we had poorly-designed ones (in high-end audio) and I’m sure of that.

Most co. still use LPS, at least with line-level components. They use cutting-edge regulators (like Hynes) and are a success.

So, if all PS’s are quieter today, where is all the noise (that is audibly reduced with conditioners, etc) coming from ? According to Shunyata Co., most of the noise was coming from our components, not the grid. Are they right ?

Some noise might be originating at home (computers, dimmers, electronics, appliances, WiFi etc.) and some is coming from the outside on power lines, from cell towers and radio stations.  Many years ago I had loud noise coming from my TV (that was in standby) resembling police communication.  Every time it happened big grey unmarked car with a lot of antennas was passing by.  His radio was likely out of wack polluting airways.  

You mentioned better results when listening at night.  In part it might be due to FCC regulation that requires radio stations to lower power at about 6PM, since signal propagation improves at night.

Would LOVE to know what percent of noise is coming from::

Our playback gear
DC motors, dimmers, WiFi in our house
The grid - neighborhood noise, radio stations, etc.

THEN to know how much total noise (in db) there is...

My own experiments without being able to measure scientifically but only with my ears reveal to me that the negative impact of the different noises pollution sources, is absolutely stupendous...Impossible to overestimate the impact...


No upgrade can gives to you what decreasing the noise floor will give and manifest through an audio system at any price : pure musicality for the first time....

It is important for me to know the noise at both ends of the PS. 

That is, great that noise inside an amp is -130dB, but if it's emitting noise back to the AC, or noise that can be radiated from power cord to interconnects that's not ideal.  I worry about this most with things like network devices and streamers. 


Best,

E

As long as your cell phone is still working you’ve got an RFI problem. If you could see RF your whole room would be lit up like a Christmas tree. 

Perspective: is it really a "rage"? "Now"?

This was something I've been working on since the early 90's, having been a subject among serious audiophiles since long before that. It was around that time when I first went out and flipped all my breakers off to see if it really would make any difference. The improvement was huge, and being so easy for anyone to do its been my standard recommendation ever since. 

There are many different kinds of noise. Its not all noise like the hiss you can hear at idle even when nothing is playing. That seems to be the noise the average guy complains about and does everything they can to get down to absolute zero. When in fact the worst kind of noise is the sort that gets interwoven right into the signal. It can be called smearing, it can be called grain, but whatever its called it does not belong and therefore its noise.

millercarbon
When in fact the worst kind of noise is the sort that gets interwoven right into the signal.

>>>>>Gee, you don’t say? Why, it almost sounds like you think the signal is the audio waveform. What is this signal you speak of? 

Here is something very interesting. We DON'T KNOW if noise is worse in recent decades, at least with RF.

I can’t seem to add the URL, so type:
"electronic noise is drowning out the internet of things ieee.org"

You didn’t read the whole article. "The bottom line is no-one really knows whether outdoor noise has increased or decreased in recent years. And the same goes for measurements made indoors."

Later says "the needed data is almost totally missing".

Yes, it says power tools and electric-toothbrushes are noisy but this obviously doesn’t affect the audiophile. Then, in a graph, it shows how "noise drops as frequency rises". And that’s just where consumer electronics is going today - ever-higher frequencies...

The number of cellphones, tablets, TVs and wireless networks has dramatically increased in the last 40 years. Plus the number of RF producing microchips in audio components have increased dramatically. You don’t have to be a rocket scientist to figure it out. RF is by definition high frequency. Hel-loo!

RF is not very high-frequency -megahertz and gigahertz ranges are. And that’s where consumer-stuff is going, to a much quieter region of energy.

Then, there’s no evidence to support the "worsening effects" of RF (as the link explained). True, if you put a fan or radio near your stereo equip. you’ll have a problem. But audiophiles have long since figured that one out.

It seems the problem is much deeper. As kijanki said above, radio station and cell-towers putting noise on the line. Then, power surges making the line-noise worse (how many people have whole-house surge protection ?).

DC motors in the house scrambling the shape of the waveform, while adding ’spikes’ at the same time. Audiophile power supplies (we were told) "rejected" noise were 1)not doing that 2)added huge amounts of noise via the rectifier and regulator.

The latest power supplies are better. But I still cringe when I think how poor the sound of audiophile systems were in the past 50 years due to poor noise-management.

You say no, I say yes, you say hello, I say goodbye. 

@jonnie22 - I have followed many of the threads on Agon and have for the most part recognised that some noises do present a significant issue, such as crackles and pops or hums when the A/C turns on - but those noises tend to be conveyed within the home along the electrical wiring.

Seems I’ve always had a very good power supply, so I have not experienced supply related noise issues.

Three years ago we moved into a new house, which also appears to have a very good power supply, so again no issues.

However - my system is now in the basement and the listening room is adjacent to the utility room which contains...
- furnace, water heater, air exchanger, two fridge/freezers
- it also has my wireless router, ethernet cables, NAS drives, modem etc..

I use "unshielded" cables throughout my system - except into the phono stage
- I use a tablet or a phone to control digital playback and
- I have a couple of small/cheap Bluetooth devices in the mix
- but the streamer is connected to the network via Ethernet cable

The result of all this "NOISE" ?
- ABSOLUTELY NOTHING !

I can turn my amp up to full volume (without playing) on either my digital input or phono input and hear nothing
- OK there is a little white noise on the phono side, but that’s pretty standard.

I can walk around my system holding a phone or tablet, even close to the cables and not hear a thing.

One might argue that the EMI/RFI generated by digital gear like phones is way above the human audible spectrum and some will debate their impact on sound quality - but I hear no evidence of sound quality degradation if I place digital devices close to components OR cables

So I too - wonder about the whole noise debate

I can only think that most noise issues may be exacerbated by the various cables employed in an audio system
- perhaps some cables act more like an antenna than others?
- perhaps some components are not well grounded, causing noise issues?

Many years ago I did try a power conditioner and YES - the sound improved
- but I do think that may have been due more to the fact that the sockets in the conditioner gripped the plugs better.

Now I use a simple "power bar" of my own construction that has
- a central power buss that all the outlets are wired too,
- a couple of small button-style breakers and
- Hospital grade breakers for MRI use (i.e. no ferrous metals).

I do a lot of cable prototyping that employs more unusual cable geometries and to date, the only noise I have encountered was with the TT to phono stage, so I reverted back the conventional shielded cable geometry for that link, which resolved that issue completely.

All of my cables use some "approaches" that I have found make a significant contribution to sound quality
- they employ a helix coil neutral conductor that is wound around the signal wire, which does provide some shielding, but I believe it operates more like a faraday cage
- the Neutral is always twice the gauge of the signal wire
- I only use a stranded, silver plated copper wire for the neutral

I ONLY use connectors that utilize materials having very good International Annealed Copper Standard (IACS) conductivity ratings
- silver plated copper is my choice material for ALL connectors

And lastly - I have always ensured everything is grounded correctly

I have no doubt that others do experience issues, but my system seems to be strangely immune to noise that others seem to have issues with.

Not much help, but perhaps something to think about.

Regards - Steve

Thanks for sharing this. I believe power cords should be shielded. Co. that make (expensive) after-market ones say this.

No power supply is quiet, unless you can prove the rectifier & regulator produce zero noise. Most rectifiers were putting huge amounts of noise on the line.

There’s lots of RF in a component -besides the rectifier, digital clocks, capacitor discharge -all radiate. Then all that metal in the component to conduct it (in phono cartridges, DAC-chips, leads on PCBs). And while we can’t hear RF, it gets ’sucked’ into the signal path and THAT gets amplified.

House wiring is probably the wrong gauge and along with a stock power cord, we were choking the ability of the noise to ’escape’ via ground-loops. Any noise in the component STAYED in the component.

Who knows what else. There’s always been a lack of studies explaining our problems. But in recent years, Shunyata Co. has brought forth some new measurements (for current delivery and noise dissipation).

In spite of acoustical room treatment and vibrational-resonance controls, electrical noise plaguing the audio system is the main reason why people dont afford Hi-Fi with the good components they already owns...

williewonka
One might argue that the EMI/RFI generated by digital gear like phones is way above the human audible spectrum and some will debate their impact on sound quality - but I hear no evidence of sound quality degradation if I place digital devices close to components OR cables.

>>>>>This brings us back to the question: What is the signal? And why is it subject to RFI/EMI, which is not only above 🔝 the human audio spectrum, it’s not even in the same spectrum? 😀 (One is the acoustic spectrum, the other is the electromagnetic spectrum.)

One might also ask why seismic vibration interferes with the signal, too, even though it’s below ⬇️ the human audio spectrum; at least it’s in the same spectrum. 🤗 By inspection the signal in all the electronics and wire is not the audio waveform. ♒️ Hope this helps.

Microphony is different issue. RF can be "overcome" IF you use a very-advanced technique like the Nordost QPoint (just demo’ed at RMAF ’19).

But it’s still best to SHIELD parts from RF, rather than "overpower" it in the air...

I suspect you missed my points. My point is that RF is not in the audio bandwidth. And the audio signal is not the audio waveform.

geoffkait is right about RF. Radio Frequency (RF) is in the mega- and giga-hertz, way above sonic, and even ultra-sonic, both of which are in the kilo-hertz region.

That alone doesn't mean it can't create a problem we can hear. A common Boy Scout science project in the 60's was to build a crystal radio. Wire and crystal, you got a radio. Self-powered. String a wire from the garage across the yard into the upstairs window. Wrap the end around and around an empty roll of toilet paper. At the other end is a crystal. Forget what that was, I was a kid. But it was necessary. The wrapping is a crude coil rheostat.

Radio waves that are everywhere all the time cross the wire, inducting a tiny bit of current in the wire. A current that varies at radio frequency, too high to hear. Just exactly the same as FM (frequency modulated) or AM (Amplitude modulated) radio. Heck you can even look at an old analog radio, it says right on it MHz, so KZOK is 102.5 mega-hertz.

I forget if its the crystal or the rheostat, but either way its just static until you tune to a particular frequency. Anyone ever tuned an old analog radio should know about static. Then when you get it right, when your wire is tuned to a particular radio frequency, then out comes sound.

Which in the Boy Scout radio is barely enough energy to vibrate the toilet paper roll if you hold your ear real close. Which you can scoff with your modern high end rig but is pretty freaking cool when you are like ten.

Okay so anyway sorry for taking so long but as you can see they have so dumbed down education that stuff a kid used to learn in Boy Scout is now beyond the education of a theoretical physicist.

Because it should be pretty obvious by now, but its not, so I'll continue explaining. So now instead of one wire across the yard we're talking about lots of wires tangled around going everywhere from the coil in the cartridge to the phono lead to the ... well you get the idea. The wire goes into the phono stage where it gets amplified 45-65 dB which is a lot. And out comes.... static and.... some damn radio station! WTF!?!?

If you haven't had this problem goody for you. I sure have. A lot of people have. So it should be pretty obvious that RFI is a thing you can hear. With your ears.

Now a bit of a conceptual leap, same thing is happening in every wire everywhere all the time. And yeah you are not gonna hear it because you can't hear mega-hertz. Until and unless something comes along and tunes the radio frequency, which could be any damn thing. 

See? Its actually pretty easy to see how RFI can be audible. I mean, if a 10 year old Boy Scout can get it....

Yeah okay so I just asked a doc here and he made one as a kid. He's 10 years younger than me. So the intense dumbing down happened after that. 

You were hearing something else. The science says we cannot hear RF directly. But as I described above, it could be getting into the circuits and getting amplified.

I went to a Jimi Hendrix concert in MD outdoors in a thunderstorm once. He was picking up a local radio station playing a guess what? Jimi Hendrix song, was it Foxy Lady?, on his electric guitar. Hendrix held his guitar up to the microphone so everyone could hear Foxy Lady, “Thank you, thank you.”

You were hearing something else. The science says we cannot hear RF directly. But as I described above, it could be getting into the circuits and getting amplified.

Um, yeah, no, that's exactly what I was hearing. Its called AM radio. Amplitude Modulation. The Radio Frequency is beyond the range of hearing. But it is modulated. Do you know what that means? It means its not all the same amplitude. Volume. The frequency stays the same but the amplitude of the frequency changes.

The rheostat coil and the crystal tune the RF signal in the wire to some specific radio frequency. When this happens you do not hear the RF itself. What you hear is the modulation in the amplitude of the RF signal. That's how radio works. Its a fact. You could look it up.

Sorry OP but I only have so much patience. You need to try. At least a little. Go back and read it again. Thanks!

No wait, seriously, I have to ask. How in the world can you be so arrogant as to tell me, especially after that explanation, that I did not hear what I in fact heard? From a science project designed and intended to accomplish that exact task? Without so much as a question or doubt? That is arrogance, right? Want to be sure and use the right word. Arrogant. Is there a better more apt term for it?

Well, your 10 paragraph response probably threw me off. All I’m saying is we cannot hear RF (directly), as it shoots through the air, in audio circuits.

BUT I admit, it’s still a problem as it gets conducted by all that metal (in a component). Hence my call for proper shielding of parts. Most high-end brands simply weren’t doing that...

As I said, the signal in electronics and wire is not the audio waveform, it’s an electromagnetic wave. Let’s call it theoretically a PURE electromagnetic wave. Unfortunately that PURE EM wave is subject to INTERNAL and EXTERNAL interference from RF and vibration, which produce NOISE or DISTORTION in the audio signal. This is why it’s necessary to reduce as much as possible ALL SOURCES of RFI and vibration. There is no substitute for Signal to Noise + Distortion Ratio. 🤗

Noise Reduction - Why the Rage?

I suspect that an an additional factor about the more recent 'buzz' (pun intended) around noise reduction is that ASR is shining a light on noise with their SINAID analysis (signal relative to noise+distortion) and then publishing a ranking of products with an occasional  reference to the actual sound quality.

This analysis may be getting a few things right and a few things wrong...but putting it all out there in this manner has to be getting the attention of a lot of companies and causing them to think about how to respond.

Take a look at post #97...and imagine that you are Border Patrol...on one hand getting a lot of accolades from many reviewers and many customers...and on the other hand getting blasted by inference that the review is not based on measurement and so how good can the product really be.

And, imagine that you are a company that has driven your SINAID numbers to vanishing low levels and you didn't think the sound was quite right...so you tweaked to get the sound where you wanted it, your SINAID numbers dropped slightly and now all of a sudden you are no longer recommended...fortunately though, your customers still love your product.

Geoff -I thought the wave carried the signal. Then, as far as RF damage -does it delay or ’erase’ the wave (or signal) ? Some links/studies would help.

And thanks snapsc, love those measurements. Esp how modern SS amps still heat up !!

The “signal” is alternating current and voltage virtually all the way from the wall outlet and power cord to the speaker terminals. The “audio waveform” per se doesn’t make its appearance until the speakers produce it. Prior to the speaker the signal is voltage and current. It’s not music until the speakers produce it.

I have not seen any studies regarding your question how RF or vibration affect the signal in wires.

So the signal magically appears at the speaker terminals, passing right over our electronics. That means delta-sigma DACs don’t affect the signal (sound different than R2Rs) etc. Thanks for the laugh.

The digital signal is not the waveform either. Good try, though. Better luck next time.

I never said the signal is part of a "waveform". I don’t know why you went off on this...

Then, read any text on the subject, going back to the 1800s and you’ll see that "the wave carries the signal". Are you disputing this ?

Gee whiz, isn’t it obvious I’m disputing this? This conversation can serve no purpose any more.